Last year somehow I burned 3 hour video to a single sided DVD. This summer I'm having trouble buring 2 hours to a DVD. Can't remember what I did. The mpg2 file is 5.7 GB. Architect won't burn it.
It's all about bitrate. When you encode an MPEG file, you specify a bitrate -- how much filespace should the encoder dedicate to each second of video. A higher bitrate results in a better quality video, but it takes up more space.
So, you can have a 3 hour video that takes up 3GB if you use a low bitrate, or you can have a 3 hour video that takes up 8GB if you use a high bitrate. Same for a 2 hour video.
If you have access to the video before it was encoded to MPEG2 (ie, you have an AVI file of it), then re-encode it to MPEG2 with a lower bitrate. (You can use a bitrate calculator to find help you pick one.) Or give the AVI to DVD Architect an use its Fit to Disc feature which will select a suitable one.
If all you've got is the MPEG2, you could try preparing the disc but not burning it, and run the prepared files through something like DVD Shrink to squeeze it down to size. Never have figured out exactly what it does, but it works. And then burn the resulting files to disc.
As Rob already mentioned, DVD Architect can encode the AVI file to MPEG2. It also has a spiffy 'fit to disc' option that will choose the proper bitrate for you.
Shrink &/or Recode go after the B frames 1st and toss out data. I think ideally losing B frame quality is less noticeable than the hit you take recompressing at lower bit rate. With Shrink as long as you stay in the 90's the result is probably OK.
Just a quick reminder, depending on the source, at more than 1 hr. 45 min. quality starts going down fast. Over 2 hours is really iffy unless you play with frames sizes. With DL discs relatively cheap now during the weekly sales, you have to ask if it's worth it.